According to one general aspect, an apparatus may include a main-branch target buffer (BTB). The apparatus may include a micro-BTB separate from and smaller than the main-BTB, and configured to produce prediction information associated with a branching instruction. The apparatus may include a micro-BTB confidence counter configured to measure a correctness of the prediction information produced by the micro-BTB. The apparatus may further include a micro-BTB misprediction rate counter configured to measure a rate of mispredictions produced by the micro-BTB. The apparatus may also include a micro-BTB enablement circuit configured to enable a usage of the micro-BTB's prediction information, based, at least in part, upon the values of the micro-BTB confidence counter and the micro-BTB misprediction rate counter.

A method is provided that includes performing, by a processor in response to a dual issue multiply instruction, multiplication of operands of the dual issue multiply instruction using multiplication units comprised in a data path of the processor and configured to operate together to determine a product of the operands, and storing, by the processor, the product in a storage location indicated by the dual issue multiply instruction.

A method is provided that includes performing, by a processor in response to a vector matrix multiply instruction, multiplying an mn matrix (A matrix) and a np matrix (B matrix) to generate elements of an mp matrix (R matrix), and storing the elements of the R matrix in a storage location specified by the vector matrix multiply instruction.

A method is provided that includes receiving, in a permute network, a plurality of data elements for a vector instruction from a streaming engine, and mapping, by the permute network, the plurality of data elements to vector locations for execution of the vector instruction by a vector functional unit in a vector data path of a processor.

A method is provided that includes performing, by a processor in response to a vector sort instruction, sorting of values stored in lanes of the vector to generate a sorted vector, wherein the values in a first portion of the lanes are sorted in a first order indicated by the vector sort instruction and the values in a second portion of the lanes are sorted in a second order indicated by the vector sort instruction; and storing the sorted vector in a storage location.

Providing reconfigurable fusion of processing elements (PEs) in vector-processor-based devices is disclosed. In this regard, a vector-processor-based device provides a vector processor including a plurality of PEs and a decode/control circuit. The decode/control circuit receives an instruction block containing a vectorizable loop comprising a loop body. The decode/control circuit determines how many PEs of the plurality of PEs are required to execute the loop body, and reconfigures the plurality of PEs into one or more fused PEs, each including the determined number of PEs required to execute the loop body. The plurality of PEs, reconfigured into one or more fused PEs, then executes one or more loop iterations of the loop body. Some aspects further include a PE communications link interconnecting the plurality of PEs, to enable communications between PEs of a fused PE and communications of inter-iteration data dependencies between PEs without requiring vector register file access operations.

A memory circuit included in a computer system stores multiple program instructions in program code. In response to fetching a loop boundary instruction, a processor circuit may store, in a loop storage circuit, a set of program instructions included in a program loop associated with the loop boundary instruction. In executing at least one iteration of the program loop, the processor circuit may retrieve the set of program instructions from the loop storage circuit.

An apparatus and method are provided for performing branch prediction. The apparatus has processing circuitry for executing instructions, and branch prediction circuitry for making branch outcome predictions in respect of branch instructions. The branch prediction circuitry includes loop prediction circuitry having a plurality of entries, where each entry is used to maintain branch outcome prediction information for a loop controlling branch instruction that controls repeated execution of a loop comprising a number of instructions. The branch prediction circuitry is arranged to analyse blocks of instructions and to produce a prediction result for each block that is dependent on branch outcome predictions made for any branch instructions appearing in the associated block. A prediction queue then stores the prediction results produced by the branch prediction circuitry in order to determine the instructions to be executed by the processing circuitry. When the block of instructions being analysed comprises a loop controlling branch instruction that has an active entry in the loop prediction circuitry, and a determined condition is detected in respect of the associated loop, the loop prediction circuitry is arranged to produce a prediction result that identifies multiple iterations of the loop. This can significantly boost prediction bandwidth for certain types of loop.

A processor includes a front end including circuitry to decode an instruction from an instruction stream and a core including circuitry to process the instruction. The core includes an execution pipeline, a dynamic core frequency logic unit, and a counter compensation logic unit. The execution pipeline includes circuitry to execute the instruction. The dynamic core frequency logic unit includes circuitry to squash a clock of the core to reduce a core frequency. The clock may not be visible to software. The counter compensation logic unit includes circuitry to adjust a performance counter increment associated with a performance counter based on at least the dynamic core frequency logic unit circuitry to squash a clock of the core to reduce a core frequency.

An apparatus and method are provided for making predictions for instruction flow changing instructions. The apparatus has a fetch queue that identifies a sequence of instructions to be fetched for execution by execution circuitry, and prediction circuitry for making predictions in respect of instruction flow changing instructions, and for controlling which instructions are identified in the fetch queue in dependence on the predictions. The prediction circuitry is arranged, during each prediction iteration, to make a prediction for a predict block comprising a sequence of M instruction addresses, in order to identify whether that predict block contains the instruction address for an instruction flow changing instruction that is predicted as taken. During each prediction iteration, the prediction circuitry is arranged by default to access a prediction storage in order to produce prediction information for instructions associated with a specified block of instruction addresses (including at least the predict block being considered), and to use that prediction information to make the prediction for the predict block. Buffer storage is used to retain the prediction information obtained from the prediction storage during one or more previous prediction iterations, and detection circuitry is used to detect when a current predict block being considered during a current prediction iteration comprises one or more instruction addresses for which the associated prediction information is retained in the buffer storage. In that event, the above default behaviour is not adopted, and an override condition is triggered to cause the prediction information for those one or more instruction addresses to be obtained from the buffer storage rather than from the prediction storage, giving rise to a power saving.